Isolates of Bacillus thuringiensis Active Against Mamestra brassicae and some Other Species: Alternatives to the Present Commercial Isolate HDI

ABSTRACT From 60 isolates of 12 varieties of Bacillus thuringiensis bioassayed in the laboratory against Mamestra brassicae, a field and glasshouse pest not controllable with HD1 (the isolate commonly used in commerce), 14 isolates had improved potency. Of these, seven in vars entomocidus and aizawi had an improvement of about 10-fold, probably adequate for practical pest control. Since some of these seven had an increased potency to Spodoptera littoralis and high potency against other pests, they are strong candidates for a valuable new product that would increase the range of pest species for practical control with B. thuringiensis.